Single-grain cosmogenic 21Ne concentrations in fluvial sediments reveal spatially variable erosion rates

Codilean, A.T., Bishop, P., Stuart, F.M. , Hoey, T.B. , Fabel, D. and Freeman, S.P.H.T. (2008) Single-grain cosmogenic 21Ne concentrations in fluvial sediments reveal spatially variable erosion rates. Geology, 36(2), pp. 159-162. (doi:10.1130/G24360A.1)

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Abstract

We evaluated the hypothesis that the spatial variation in erosion in a catchment is reflected in the distribution of the cosmogenic nuclide concentrations in sediments leaving the catchment. Using published data and four new 10Be measurements in fluvial sediment collected from the outlets of small river catchments, we constrained the spatial variability of erosion rates in the Gaub River catchment in Namibia. We combined these catchment-averaged erosion rates, and the mean slope values with which they are associated, in a digital elevation model (DEM)–based analysis to predict distributions of cosmogenic 21Ne concentrations in the sediment leaving the Gaub catchment. We compared these synthetic distributions with the distribution of concentrations of cosmogenic 21Ne (21NeC) in 32 quartz fluvial pebbles (16–21 mm) collected from the catchment outlet. The 21NeC concentrations span nearly two orders of magnitude (2.6–160 × 106 atoms/g) and are highly skewed toward low values. The DEM-based analysis confirms this skew—the measured 21NeC distribution plots within the envelope of distributions predicted for the catchment. This match between measured and synthetic 21Ne distributions implies that the measured distribution is a signature of the spatial variation in erosion rates.

Item Type:Articles
Additional Information:Awarded the British Society for Geomorphology’s Chorley Award in 2008 for the best paper published by a recent PhD student
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Hoey, Professor Trevor and Codilean, Dr Alexandru and Bishop, Professor Paul and Fabel, Dr Derek and Freeman, Professor Stewart and Stuart, Professor Finlay
Authors: Codilean, A.T., Bishop, P., Stuart, F.M., Hoey, T.B., Fabel, D., and Freeman, S.P.H.T.
Subjects:G Geography. Anthropology. Recreation > GB Physical geography
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Geology
ISSN:0091-7613

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